Travel route generation system and vehicle driving assistance system

ABSTRACT

A vehicle driving assistance system includes a travel route generation system that acquires travel road information and obstacle information acquired by sensor(s), and generates the target travel route, on which a host vehicle travels, on a travel road. When the host vehicle changes lanes, the system acquires information on three peripheral vehicles, which exist near the host vehicle, on a change destination lane from the obstacle information, sets a target space, to which the host vehicle 1 should move, between two each of the three peripheral vehicles on the change destination lane based on this information on the three peripheral vehicles, predicts a change in size of each of the target spaces, and generates the target travel route, on which the host vehicle travels during the lane change, on the basis of this predicted change in the size of each of the target spaces.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to Japanese patent applicationJP 2020-022370, filed Feb. 13, 2020, the entire contents of which beingincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a travel route generation system thatgenerates a travel route of a vehicle and a vehicle driving assistancesystem that assists with driving of the vehicle on the basis of thetravel route.

BACKGROUND ART

Conventionally, a technique of setting a target travel route on which ahost vehicle travels on the basis of a surrounding situation of the hostvehicle and a state of the host vehicle and assisting with driving ofthe vehicle on the basis of this target travel route (more specifically,driving assist control and automated driving control) has beendeveloped. For example, in Patent document 1, a technique of setting astart point and an end point of a lane change on the basis ofinformation on the host vehicle, information on another vehicle aroundthe host vehicle, and the like and generating the target travel routeaccording to these points at the time of the lane change is disclosed.

PRIOR ART DOCUMENTS Patent Documents

[Patent document 1] JP-A-2017-100657

SUMMARY Problems to be Solved

The inventor of the present application has considered that the targettravel route, on which the host vehicle can move safely betweenperipheral vehicles existing on a change destination lane (typically,between a preceding vehicle and a following vehicle existing near thehost vehicle) when the host vehicle changes a lane, is desirablygenerated. In this case, in order to appropriately secure the safetyduring the lane change, it is desired to accurately recognize a spacebetween the peripheral vehicles, to which the host vehicle moves, on thechange destination lane. More specifically, it is desired to accuratelyrecognize a position and size of the space between the peripheralvehicles that are changed according to the peripheral vehicles, each ofwhich moves at various speeds from time to time.

In Patent document 1 described above, the description is only made thatthe target travel route is generated during the lane change, and theproblem on which the inventor of the present application has focused isnot disclosed at all. Naturally, a technique capable of solving thisproblem is neither disclosed nor suggested.

The present disclosure has been made to solve the above-described, andother, problems and therefore has a purpose of providing a travel routegeneration system and a vehicle driving assistance system, the travelroute generation system capable of appropriately generating a targettravel route through which a host vehicle can move safely to a positionbetween peripheral vehicles on a change destination lane when the hostvehicle changes the lane, and the vehicle driving assistance systemcapable of assisting with driving of the vehicle on the basis of thistarget travel route.

Means for Solving the Problem

In order to achieve the above purpose, the present disclosure provides atravel route generation system having: a travel road informationacquisition sensor that acquires travel road information on a travelroad of a host vehicle; an obstacle information acquisition sensor thatacquires obstacle information on an obstacle on the travel road; and anarithmetic device (such as circuitry) configured to generate a targettravel route, on which the host vehicle travels, in the travel roadbased on the travel road information and the obstacle information. Thearithmetic device is configured to: acquire information on at least twoperipheral vehicles, which exist near the host vehicle on a changedestination lane, from the obstacle information under a condition it isplanned for the host vehicle to change lanes; set a target space, towhich the host vehicle should move, between the at least two peripheralvehicles in the change destination lane based on the information on theat least two peripheral vehicles; and predict a change in size of thetarget space; and generate the target travel route, on which the hostvehicle travels during a lane change operation, based on the predictedchange in the size of the target space.

According to the present disclosure that is configured as describedabove, in the case where the host vehicle changes the lane, thearithmetic device sets the target space, to which the host vehicleshould move, between the peripheral vehicles in the change destinationlane, predicts the change in the size of the target space (correspondingto a length of the target space along a stretching direction of thetravel road), and generates the target travel route, on which the hostvehicle travels during the lane change. In this way, it is possible toaccurately recognize the size of the space between the peripheralvehicles that is changed according to the peripheral vehicles, each ofwhich moves at various speeds from time to time. Therefore, according tothe present disclosure, when the host vehicle changes the lane on thebasis of the target travel route, the host vehicle can safely move tothe position between the peripheral vehicles on the change destinationlane.

In the present disclosure, the arithmetic device is configured to:acquire information on a first peripheral vehicle that exists on thechange destination lane, information on the second peripheral vehiclethat exists behind the first peripheral vehicle, and information on athird peripheral vehicle that exists behind the second peripheralvehicle as the information on the at least two peripheral vehicles; seta first target space between the first peripheral vehicle and the secondperipheral vehicle and a second target space between the secondperipheral vehicle and the third peripheral vehicle as the target spaceson the basis of the information on the first, second, and thirdperipheral vehicles; select one of the first and second target spaces onthe basis of the change in the size of each of the first and secondtarget spaces; and generate the target travel route on the basis of theselected target space.

According to the present disclosure that is configured as describedabove, the arithmetic device sets the two target spaces (the first andsecond target spaces) on the change destination lane, selects one of thetarget spaces on the basis of the change in the size of each of thesetwo target spaces, and generates the target travel route on the basis ofthe selected target space. In this way, of the spaces between the twoperipheral vehicles existing near the host vehicle on the changedestination lane, the space that is adequate for movement of the hostvehicle is accurately adopted, and the target travel route can therebybe generated.

In the present disclosure, preferably, the arithmetic device isconfigured to select the target space that is increased in the casewhere one of the first and second target spaces is increased while theother is not increased.

This is because it is considered that the host vehicle can move moresafely to the increased target space than to the reduced target space.According to the present disclosure that is configured as describedabove, it is possible to accurately adopt the target space, to which thehost vehicle can move further safely for the lane change.

In the present disclosure, preferably, the arithmetic device isconfigured to select the target space with a lower change rate of thesize in the case where both of the first and second target spaces arenot increased.

This is because it is considered that the host vehicle can move safelyto the target space with a smaller change rate in size in the case whereboth of the first and second target spaces are reduced or are inconstant size. Also, according to the present disclosure that isconfigured as described above, it is possible to accurately adopt thetarget space, to which the host vehicle can move further safely for thelane change.

In the present disclosure, preferably, the arithmetic device isconfigured to select the larger target space of the first and secondtarget spaces in the case where both of the first and second targetspaces are reduced and the size of one or both of the first and secondtarget spaces is equal to or larger than a specified value.

This is because it is considered that that the host vehicle moves safelyto this target space when the target space is reduced but is still largeenough. Also, according to the present disclosure that is configured asdescribed above, it is possible to accurately adopt the target space, towhich the host vehicle can move further safely for the lane change.

In the present disclosure, preferably, the arithmetic device selects thesecond target space in the case where the change in the size of thefirst and second target spaces is substantially the same.

This is because it is considered to be safer when the host vehicle 1 isdecelerated during the lane change and moves to the second target spaceat the rear than when the host vehicle 1 is accelerated during the lanechange and moves to the first target space in front in the case wherechange states of the first and second target spaces are the same. Also,according to the present disclosure that is configured as describedabove, it is possible to accurately adopt the target space, to which thehost vehicle can move further safely for the lane change.

In the present disclosure, preferably, the arithmetic device isconfigured to: set a dangerous area that the host vehicle does not enteraround each of the at least two peripheral vehicles on the basis of theinformation on the at least two peripheral vehicles; set the targetspace between the dangerous areas that are set around the at least twoperipheral vehicles; and set a portion stretched behind the peripheralvehicle in the dangerous area to be longer than a portion stretchedahead of the peripheral vehicle therein.

According to the present disclosure that is configured as describedabove, the target space is set on the basis of the dangerous area thatis set around each of the peripheral vehicles. Thus, when the hostvehicle changes the lane and moves to the target space on the basis ofthe target travel route, it is possible to effectively prevent acollision of the host vehicle with the peripheral vehicle. In addition,according to the present disclosure, the portion behind the peripheralvehicle in the dangerous area is set to be longer than the portion aheadof the peripheral vehicle therein. Thus, it is possible to effectivelyprevent the collision of the host vehicle with the peripheral vehicle inthe case where the peripheral vehicle (particularly, a precedingvehicle) is decelerated during the lane change of the host vehicle.

In the present disclosure, preferably, the arithmetic device isconfigured to generate such a target travel route that the host vehiclestarts changing the lane when a relative speed between a speed of thehost vehicle and a moving speed of the target space becomes lower than aspecified speed.

According to the present disclosure that is configured as describedabove, when the host vehicle changes the lane on the basis of the targettravel route, the host vehicle can safely and reliably move to thetarget space.

In the present disclosure, preferably, the arithmetic device isconfigured to: generate the target travel route, on which the hostvehicle travels during the lane change, on the basis of the predictedchange in the size of the target space in the case where a distance to apoint, at which the host vehicle should change the lane, is shorter thana specified distance; and predict a future position of the target spaceon the basis of the moving speed of the target space and generate thetarget travel route, on which the host vehicle travels during the lanechange, on the basis of the predicted future position in the case wherethe distance to the point, at which the host vehicle should change thelane, is equal to or longer than the specified distance.

According to the present disclosure that is configured as describedabove, it is possible to appropriately switch processing to generate thetarget travel route on the basis of the target space according towhether the point, at which the host vehicle should change the lane, islocated far away from or near the host vehicle.

In another aspect, in the present disclosure, a vehicle drivingassistance system has a controller that is configured to execute drivingcontrol of a vehicle such that the vehicle travels along a travel routegenerated by the above-described travel route generation system.

Advantages

The travel route generation system according to the present disclosurecan appropriately generate the target travel route through which thehost vehicle can safely move to the position between the peripheralvehicles on the change destination lane when the host vehicle changesthe lane. The vehicle driving assistance system according to the presentdisclosure can appropriately assist with driving of the vehicle on thebasis of such a target travel route.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a schematic configuration of avehicle driving assistance system to which a travel route generationsystem according to an embodiment of the present disclosure is applied.

FIG. 2 is an explanatory view of a method for generating a target travelroute on which a host vehicle travels during a lane change in the casewhere a point at which the host vehicle should change the lane islocated relatively far away in the embodiment of the present disclosure.

FIG. 3 is an explanatory view of a method for generating the targettravel route on which the host vehicle travels during the lane change inthe case where the point at which the host vehicle should change thelane is located relatively close to the host vehicle in the embodimentof the present disclosure.

FIG. 4 is a flowchart illustrating overall processing according to theembodiment of the present disclosure.

FIG. 5 is a flowchart illustrating first processing according to theembodiment of the present disclosure.

FIG. 6 is a flowchart illustrating second processing according to theembodiment of the present disclosure.

FIG. 7 is a flowchart illustrating target space following processingaccording to the embodiment of the present disclosure.

MODES FOR CARRYING OUT THE DISCLOSURE

A description will hereinafter be made on a travel route generationsystem and a vehicle driving assistance system according to anembodiment of the present disclosure with reference to the accompanyingdrawings.

[System Configuration]

A description will firstly be made on a configuration of the vehicledriving assistance system, to which the travel route generation systemaccording to the embodiment of the present disclosure is applied, withreference to FIG. 1. FIG. 1 is a block diagram illustrating a schematicconfiguration of the vehicle driving assistance system to which thetravel route generation system according to the embodiment of thepresent disclosure is applied.

A vehicle driving assistance system 100 has a function as the travelroute generation system that sets a target travel route, on which avehicle (hereinafter appropriately referred to as a “host vehicle”) 1travels, on a travel road, and is configured to execute drivingassistance control (driving assist control and automated drivingcontrol) to cause the vehicle 1 to travel along this target travelroute. As illustrated in FIG. 1, the vehicle driving assistance system100 has an electronic control unit (ECU) 10 as an arithmetic device anda controller, plural types of sensors, and plural control systems.

More specifically, the plural types of the sensors are a camera 21, aradar 22, a vehicle speed sensor 23 for detecting behavior of thevehicle 1 and a driving operation by an occupant, an acceleration sensor24, a yaw rate sensor 25, a steering angle sensor 26, an acceleratorsensor 27, and a brake sensor 28. The plural types of the sensorsfurther include a positioning system 29 for detecting a position of thevehicle 1 and a navigation system 30. The plural control systems are anengine control system 31, a brake control system 32, and a steeringcontrol system 33.

Moreover, other types of the sensors may be a peripheral sonar systemfor measuring a distance and a position of a peripheral structure withrespect to the vehicle 1, a corner radar provided at each of fourcorners of the vehicle 1 to measure an approach of the peripheralstructure, and an inner camera for capturing an image of the inside of acabin of the vehicle 1.

The ECU 10 performs various calculations on the basis of signalsreceived from the plural types of the sensors, and sends control signalsto the engine control system 3 l, the brake control system 32, and thesteering control system 33 so as to appropriately actuate an enginesystem, a brake system, and a steering system, respectively. The ECU 10is constructed of a computer that includes one or more processors(typically CPUs), memory (ROM, RAM, or the like) for storing variousprograms, an input/output device, and the like. The ECU 10 correspondsto an example of the “arithmetic device” and an example of the“controller” in the present disclosure, and may be implemented as acomputer, and/or computer circuitry, and/or logic device(s), such asapplication specific integrated circuits, configured by software (heldin memory) and/or firmware settings to perform the specified operationsdescribed herein.

The camera 21 captures an image around the vehicle 1, and outputs imagedata. Based on the image data received from the camera 21, the ECU 10identifies objects (for example, a preceding vehicle (a forwardvehicle), a following vehicle (a rear vehicle), a parked vehicle, apedestrian, a travel road, road marking lines (a lane divider, a whiteline, and a yellow line), a traffic signal, a traffic sign, a stop line,an intersection, an obstacle, and the like). The ECU 10 may acquireinformation on the object from the outside through a trafficinfrastructure, inter-vehicle communication, or the like. In this way, atype, a relative position, a moving direction, and the like of theobject are identified.

The radar 22 measures a position and a speed of the object(particularly, the preceding vehicle, the following vehicle, the parkedvehicle, the pedestrian, a dropped object on the travel road, or thelike). For example, a millimeter-wave radar can be used as the radar 22.The radar 22 transmits a radio wave in an advancing direction of thevehicle 1, and receives a reflected wave that is generated when theobject reflects the transmitted wave. Then, based on the transmittedwave and the received wave, the radar 22 measures a distance between thevehicle 1 and the object (for example, an inter-vehicular distance) anda relative speed of the object to the vehicle 1. In this embodiment,instead of the radar 22, a laser radar, an ultrasonic sensor, or thelike may be used to measure the distance from the object and therelative speed of the object. Alternatively, the plural types of thesensors may be used to constitute a position and speed measuring device.

The camera 21 and the radar 22 correspond to an example of the “travelroad information acquisition device” and an example of the “obstacleinformation acquisition device” in the present disclosure. For example,“travel road information” includes information on a shape of the travelroad (a straight road, a curved road, or a curvature of the curvedroad), a travel road width, the number of lanes, a lane width,regulation information of the travel road designated on the traffic signor the like (a speed limit or the like), the intersection, a crosswalk,and the like. “Obstacle information” includes information on presence orabsence of the obstacle on the travel road of the vehicle 1 (forexample, the object, such as the preceding vehicle, the followingvehicle, the parked vehicle, or the pedestrian, that can possibly be theobstacle in travel of the vehicle 1), a moving direction of theobstacle, and a moving speed of the obstacle, and the like.

The vehicle speed sensor 23 detects an absolute speed of the vehicle 1.The acceleration sensor 24 detects acceleration of the vehicle 1. Thisacceleration includes acceleration in a longitudinal direction andacceleration in a lateral direction (that is, lateral acceleration). Theacceleration includes not only a change rate of the speed in a speedincreasing direction but also a change rate of the speed in a speedreducing direction (that is, deceleration).

The yaw rate sensor 25 detects a yaw rate of the vehicle 1. The steeringangle sensor 26 detects a rotation angle (a steering angle) of asteering wheel of the vehicle 1. The ECU 10 executes a specifiedcalculation on the basis of the absolute speed detected by the vehiclespeed sensor 23 and the steering angle detected by the steering anglesensor 26, and can thereby acquire a yaw angle of the vehicle 1. Theaccelerator sensor 27 detects a depression amount of an acceleratorpedal. The brake sensor 28 detects a depression amount of a brake pedal.

The positioning system 29 is a GPS system and/or a gyroscopic system,and detects the position of the vehicle 1 (current vehicle positioninformation). The navigation system 30 stores map information therein,and can provide the map information to the ECU 10. Based on the mapinformation and the current vehicle position information, the ECU 10identifies a road, the intersection, the traffic signal, a building, andthe like existing around (particularly, in the advancing direction of)the vehicle 1. The map information may be stored in the ECU 10. Thenavigation system 30 also corresponds to an example of the “travel roadinformation acquisition device” in the present disclosure.

The engine control system 31 controls an engine of the vehicle 1. Theengine control system 31 is a component capable of regulating engineoutput (drive power) and, for example, includes an ignition plug, a fuelinjection valve, a throttle valve, a variable valve mechanism thatchanges opening/closing timing of intake/exhaust valves, and the like.When the vehicle 1 has to be accelerated or decelerated, the ECU 10sends the control signal to the engine control system 31 so as to changethe engine output.

The brake control system 32 controls the brake system of the vehicle 1.The brake control system 32 is a component capable of regulating abraking force of the brake system and, for example, includes a hydraulicpump, a valve unit, and the like. When the vehicle 1 has to bedecelerated, the ECU 10 sends the control signal to the brake controlsystem 32 so as to generate the braking force.

The steering control system 33 controls a steering device of the vehicle1. The steering control system 33 is a component capable of regulatingthe steering angle of the vehicle 1 and, for example, includes anelectric motor for an electric power steering system, and the like. Whenthe advancing direction of the vehicle 1 has to be changed, the ECU 10sends the control signal to the steering control system 33 so as tochange a steering direction. Each of the control systems 31, 32, and/or33 may be implemented with processing circuitry (e.g., one or moreprogrammable devices, such as a micro controller, and/or dedicatedcircuitry such as one or more ASICs, or combinations thereof to executethe operations described herein.

[Generation of Target Travel Route]

Next, a description will be made on generation of the target travelroute by the above-described ECU 10 in the embodiment of the presentdisclosure. First, a description will be made on a brief summary thereofwith reference to FIG. 2 and FIG. 3.

FIG. 2 is an explanatory view of a method for generating the targettravel route on which the host vehicle 1 travels during a lane change inthe case where a point at which the host vehicle 1 should change thelane is located relatively far away (in the case where a distancebetween the host vehicle 1 and the point at which the vehicle 1 shouldchange the lane is equal to or longer than a specified distance (1 km inone example), for example, in the case where a merging point or abranched point at which the lane change is necessary is locatedrelatively far away. In FIG. 2, a current situation around the hostvehicle 1 is illustrated in an upper section, a situation around thehost vehicle 1 that is predicted after a lapse of a first time (forexample, three seconds) from current time is illustrated in a middlesection, and a situation around the host vehicle 1 that is predictedafter a lapse of a second time (a longer time than the first time, forexample, six seconds) from the current time is illustrated in a lowersection. In this embodiment, in a period from the current time to thelapse of the second time, the ECU 10 repeatedly predicts the situationaround the host vehicle 1 in specified cycles. This second time isusually set on the basis of a time required for the vehicle to changethe lane.

First, in the case where the host vehicle 1 changes the lane, the ECU 10acquires information on peripheral vehicles 3 a, 3 b, which exist nearthe host vehicle 1 on an adjacent lane as a change destination, from theabove obstacle information. In this case, the ECU 10 basically acquiresthe information on the two peripheral vehicles 3 a, 3 b that are locatedthe closest to the host vehicle 1 on the adjacent lane as the changedestination. In detail, the ECU 10 acquires the information on theperipheral vehicle 3 a and the information on the peripheral vehicle 3b. The peripheral vehicle 3 a is the preceding vehicle, which is locatedthe closest to the host vehicle 1, on the adjacent lane, and theinformation on the peripheral vehicle 3 b is the following vehicle,which is located the closest to the host vehicle 1, on the adjacentlane. In this embodiment, in the case where the point at which the hostvehicle 1 should change the lane is located relatively far away, thereis a tendency that a distance between the peripheral vehicles on theadjacent lane is long (in other words, there is a tendency that theperipheral vehicles on the adjacent lane are relatively scarce). Inaddition, both of a sufficient time and the sufficient distance for thelane change are available. Thus, the ECU 10 only considers a singlespace between the peripheral vehicles, to which the host vehicle 1 movesfor the lane change, when setting the target travel route for the lanechange, that is, the ECU 10 only considers the two peripheral vehicles 3a, 3 b that form the single space. That is, the ECU 10 focuses onrecognition of the single space between the peripheral vehicles.

Next, the ECU 10 respectively sets dangerous areas 40 a 1, 40 b 1 aroundthe peripheral vehicles 3 a, 3 b on the basis of the acquiredinformation on the peripheral vehicles 3 a, 3 b. The dangerous areas 40a 1, 40 b 1 are provided to prevent entry of the host vehicle 1 in thedriving assistance based on the target travel route. More specifically,the ECU 10 sets the dangerous areas 40 a 1, 40 b 1 on the basis of arelative speed and a relative distance (an inter-vehicular distance)between the host vehicle 1 and each of the peripheral vehicles 3 a, 3 b,and the like. For example, the ECU 10 calculates time-headway (THW)and/or a time to collision (TTC) between the vehicle 1 and each of theperipheral vehicles 3 a, 3 b on the basis of these relative speed andrelative distance, and sets the dangerous areas 40 a 1, 40 b 1 from thecalculated THW and/or TTC. The THW is calculated by dividing therelative distance between the host vehicle 1 and each of the peripheralvehicles 3 a, 3 b by a speed of the host vehicle 1. The TTC iscalculated by dividing the relative distance between the host vehicle 1and each of the peripheral vehicles 3 a, 3 b by the relative speedbetween the host vehicle 1 and each of the peripheral vehicles 3 a, 3 b.

In addition, the ECU 10 sets portions stretched behind the peripheralvehicles 3 a, 3 b in the dangerous areas 40 a 1, 40 b 1 to be longerthan portions stretched in front of the peripheral vehicles 3 a, 3 b inthe dangerous areas 40 a 1, 40 b 1. A reason therefor is as follows.When a case where the host vehicle 1 cuts in front of one of theperipheral vehicles 3 a, 3 b is considered, in this case, a driver ofcorresponding one of the peripheral vehicles 3 a, 3 b is basicallylooking ahead. Thus, there is a low possibility that the driver of oneof the peripheral vehicles 3 a, 3 b accelerates corresponding one of theperipheral vehicles 3 a, 3 b. Rather, this driver is likely todecelerate corresponding one of the peripheral vehicles 3 a, 3 b. As aresult, it is considered that the peripheral vehicles 3 a, 3 b, whichtravel on the adjacent lane, are more likely to be decelerated thanaccelerated. For such a reason, it is considered that a collision of thehost vehicle 1 with a rear portion of one of the peripheral vehicles 3a, 3 b at the time when the host vehicle 1 changes the lane andcorresponding one of the peripheral vehicles 3 a, 3 b is deceleratedshould preferentially be prevented over a collision of the host vehicle1 with a front portion of one of the peripheral vehicles 3 a, 3 b at thetime when the host vehicle 1 changes the lane and corresponding one ofthe peripheral vehicles 3 a, 3 b is accelerated. Thus, in thisembodiment, the ECU 10 sets the portions behind the peripheral vehicles3 a, 3 b in the dangerous areas 40 a 1, 40 b 1 to be longer than theportions in front of the peripheral vehicles 3 a, 3 b therein asdescribed above. In this way, it is possible to effectively prevent thecollision of the host vehicle 1 with one of the peripheral vehicles 3 a,3 b in the case where corresponding one of the peripheral vehicles 3 a,3 b is decelerated during the lane change of the host vehicle 1.

Next, between the thus-set dangerous area 40 a 1 and dangerous area 40 b1, the ECU 10 sets a target space SP1 a, to which the host vehicle 1should move by the lane change, on the adjacent lane. A length of thetarget space SP1 a along a stretching direction of the travel roadcorresponds to a distance between the dangerous area 40 a 1 and thedangerous area 40 b 1, and a length (a width) of the target space SP1 aalong a width direction of the travel road corresponds to a length (awidth) of each of the dangerous areas 40 a 1, 40 b 1 along the widthdirection of the travel road. In addition, the ECU 10 sets a targetpoint P1 a in the target space SP1 a, and the target point P1 a servesas a travel mediating point that is used when the target travel routefor the lane change is set. More specifically, the ECU 10 sets thetarget point P1 a at a center of the target space SP1 a.

Thereafter, in the period from the current time to the lapse of thesecond time, the ECU 10 repeatedly predicts the situation around thehost vehicle 1 in the specified cycles. As illustrated in the middlesection of FIG. 2, in the middle of the period from the current time tothe lapse of the second time, more specifically, after the lapse of thefirst time from the current time, the ECU 10 predicts dangerous areas 40a 2, 40 b 2 of the peripheral vehicles 3 a, 3 b. In this case, the ECU10 predicts, the relative speed, the relative distance (theinter-vehicular distance), and the like between the host vehicle 1 andeach of the peripheral vehicles 3 a, 3 b after the first time, and basedon these relative speed, relative distance, and the like, sets thedangerous areas 40 a 2, 40 b 2 by a similar method to that describedabove.

Next, the ECU 10 sets a target space SP1 b between the set dangerousarea 40 a 2 and the set dangerous area 40 b 2, and also sets a targetpoint P1 b at a center of this target space SP1 b. Then, the ECU 10calculates the speed of the host vehicle 1, at which the host vehicle 1follows the target point P1 b, on the basis of a relative speed and arelative distance between the host vehicle 1 and the target point P1 b.Based on the relative speed between the speed of this host vehicle 1 andthe speed of the peripheral vehicle 3 a as the preceding vehicle, andthe like, the ECU 10 determines a possibility of a collision of the hostvehicle 1 with the peripheral vehicle 3 a at the time when the hostvehicle 1 changes the lane. In the example illustrated in FIG. 2, theECU 10 determines that there is no possibility of the collision, andkeeps predicting the situation around the host vehicle 1 even after thelapse of the first time.

Thereafter, as illustrated in the lower section of FIG. 2, after thelapse of the second time from the current time, that is, after a lapseof a time required for the lane change, the ECU 10 predicts dangerousareas 40 a 3, 40 b 3 of the peripheral vehicles 3 a, 3 b. In this case,the ECU 10 predicts, the relative speed, the relative distance (theinter-vehicular distance), and the like between the host vehicle 1 andeach of the peripheral vehicles 3 a, 3 b after the second time, andbased on these relative speed, relative distance, and the like, sets thedangerous areas 40 a 3, 40 b 3 by a similar method to that describedabove. Next, the ECU 10 sets a target space SP1 c between the setdangerous area 40 a 3 and the set dangerous area 40 b 3, and also sets atarget point P1 c at a center of this target space SP1 c. Then, the ECU10 calculates the speed of the host vehicle 1, at which the host vehicle1 follows the target point P1 c, on the basis of a relative speed and arelative distance between the host vehicle 1 and the target point P1 c.Based on the relative speed between the speed of this host vehicle 1 andthe speed of the peripheral vehicle 3 a as the preceding vehicle, andthe like, the ECU 10 determines a possibility of a collision of the hostvehicle 1 with the peripheral vehicle 3 a at the time when the hostvehicle 1 changes the lane. In the example illustrated in FIG. 2, theECU 10 determines that there is no possibility of the collision.

Next, the ECU 10 further determines whether the relative distancebetween the host vehicle 1 and the target point P1 c is shorter than aspecified distance (for example, 5 m) and the relative speed between thehost vehicle 1 and the target point P1 c is lower than a specified speed(for example, 5 to 10 km). In the example illustrated in FIG. 2, the ECU10 determines that the relative distance is shorter than the specifieddistance and that the relative speed is lower than the specified speed.Then, the ECU 10 decides to adopt the target point P1 c as the travelmediating point, and sets a route L1 that connects the current positionof the host vehicle 1 and the travel mediating point P1 c (for example,the route L1 may be generated by using a specified curve (a polynomialfunction or the like)) as the target travel route for the lane change.Driving control is executed by using such a target travel route L1. Insuch a case, when the relative speed between the speed of the hostvehicle 1 and a moving speed of the target point P1 c (primarily, amoving speed of the target space SP1 c) is lower than the specifiedspeed after the lapse of the second time from the current time, the hostvehicle 1 starts changing the lane. Furthermore, the ECU 10 sets thespeed, which should be applied to the host vehicle 1, on the abovetarget travel route L1. In the example illustrated in FIG. 2, the ECU 10sets such a speed that decelerates the host vehicle 1 (see an arrow A1)for the lane change.

The example in which both of the peripheral vehicle 3 a as the precedingvehicle and the peripheral vehicle 3 b as the following vehicle existnear the host vehicle 1 has been described above. However, in the casewhere one of such a preceding vehicle and such a following vehicle doesnot exist, the target space may be set at a position with a sufficientmargin being provided from the existing peripheral vehicle (the sameapplies to an example illustrated in FIG. 3). For example, in the casewhere only the preceding vehicle exists, a space from a rear end of thepreceding vehicle to a position away therefrom by a specified distancemay be set as the target space. In the case where only the followingvehicle exists, a space from a front end of the following vehicle to aposition away therefrom by the specified distance may be set as thetarget space.

Next, FIG. 3 is an explanatory view of a method for generating thetarget travel route on which the host vehicle 1 travels during the lanechange in the case where the point at which the host vehicle 1 shouldchange the lane is located relatively close to the host vehicle 1 (inthe case where the distance between the host vehicle 1 and the point atwhich the vehicle 1 should change the lane is shorter than the specifieddistance (1 km in one example), for example, in the case where themerging point or the branched point at which the lane change isnecessary is located relatively close to the host vehicle 1. In FIG. 3,the current situation around the host vehicle 1 is illustrated in anupper section, a situation around the host vehicle 1 that is predictedafter the lapse of the first time (for example, three seconds) from thecurrent time is illustrated in a middle section, and a situation aroundthe host vehicle 1 that is predicted after the lapse of the second time(for example, six seconds) from the current time is illustrated in alower section. Similar to the above, in the period from the current timeto the lapse of the second time (usually set on the basis of the timerequired for the vehicle to change the lane), the ECU 10 repeatedlypredicts the situation around the host vehicle 1 in the specifiedcycles. Hereinafter, a description on the same contents as those in FIG.2 will appropriately be omitted.

First, in the case where the host vehicle 1 changes the lane, the ECU 10acquires information on peripheral vehicles 3 c, 3 d, 3 e, which existnear the host vehicle 1 on the adjacent lane as the change destination,from the above obstacle information. In this case, the ECU 10 basicallyacquires the information on the three peripheral vehicles 3 c, 3 d, 3 ethat are located the closest to the host vehicle 1 on the adjacent laneas the change destination. In detail, the ECU 10 uses the peripheralvehicle 3 d, which is the preceding vehicle located the closest to thehost vehicle 1 on the adjacent lane, the peripheral vehicle 3 c, whichis the preceding vehicle of this peripheral vehicle 3 d, and theperipheral vehicle 3 e, which is the following vehicle located theclosest to the host vehicle 1 on the adjacent lane. In this embodiment,in the case where the point at which the host vehicle 1 should changethe lane is located relatively close to the host vehicle 1, there is thetendency that the distance between the peripheral vehicles on theadjacent lane is short (in other words, there is a tendency that theperipheral vehicles on the adjacent lane are relatively dense). Inaddition, both of the time and the distance for the lane change areinsufficient. Thus, the ECU 10 considers two spaces as candidates for aspace between the peripheral vehicles, to which the host vehicle 1 movesfor the lane change, when setting the target travel route for the lanechange, that is, the ECU 10 considers the three peripheral vehicles 3 c,3 d, 3 e that provide the two spaces. That is, the ECU 10 uses the twospaces as the candidates and compares these spaces so as to finallyselect the single space for the setting of the target travel route.

Next, based on acquired information on the peripheral vehicles 3 c, 3 d,3 e, more specifically, based on a relative speed, a relative distance(an inter-vehicular distance), and the like between the host vehicle 1and each of the peripheral vehicles 3 c, 3 d, 3 e, the ECU 10 setsdangerous areas 40 c 1, 40 d 1, 40 e 1 around the peripheral vehicles 3c, 3 d, 3 e, respectively. In this case, the ECU 10 sets portions behindthe peripheral vehicles 3 c, 3 d, 3 e in the dangerous areas 40 c 1, 40d 1, 40 e 1 to be longer than portions in front of the peripheralvehicles 3 c, 3 d, 3 e therein. Next, the ECU 10 sets a target space SP2a between the dangerous area 40 c 1 and the dangerous area 40 d 1, andalso sets a target point P2 a at a center of this target space SP2 a. Inaddition, the ECU 10 sets a target space SP3 a between the dangerousarea 40 d 1 and the dangerous area 40 e 1, and also sets a target pointP3 a at a center of this target space SP3 a.

Thereafter, in the period from the current time to the lapse of thesecond time, the ECU 10 repeatedly predicts the situation around thehost vehicle 1 in the specified cycles. As illustrated in the middlesection of FIG. 3, in the middle of the period from the current time tothe lapse of the second time, more specifically, after the lapse of thefirst time from the current time, the ECU 10 predicts dangerous areas 40c 2, 40 d 2, 40 e 2 of the peripheral vehicles 3 c, 3 d, 3 e. Next, theECU 10 sets a first target space SP2 b between the dangerous area 40 c 2and the dangerous area 40 d 2, and also sets a first target point P2 bat a center of this first target space SP2 b. In addition, the ECU 10sets a second target space SP3 b between the dangerous area 40 d 2 andthe dangerous area 40 e 2, and also sets a second target point P3 b at acenter of this second target space SP3 b.

Thereafter, as illustrated in the lower section of FIG. 3, after thelapse of the second time from the current time, that is, after the lapseof the time required for the lane change, the ECU 10 predicts dangerousareas 40 c 3, 40 d 3, 40 e 3 of the peripheral vehicles 3 c, 3 d, 3 e.Next, the ECU 10 sets a first target space SP2 c between the dangerousarea 40 c 3 and the dangerous area 40 d 3, and also sets a first targetpoint P2 c at a center of this first target space SP2 c. In addition,the ECU 10 sets a second target space SP3 c between the dangerous area40 d 3 and the dangerous area 40 e 3, and also sets a second targetpoint P3 c at a center of this second target space SP3 c.

Next, based on changes in size (meaning a length along the stretchingdirection of the travel road, and the same applies below) of the firstand second target spaces SP2 c, SP3 c after the second time with respectto the first and second target spaces SP2 a, SP2 b, SP3 a, SP3 b so far,the ECU 10 selects one of the first and second target spaces SP2 c, SP3c as the target space that is used when setting the target travel routefor the lane change. That is, the ECU 10 selects one of the first andsecond target spaces SP2 c, SP3 c that is appropriate as a space, towhich the host vehicle 1 should move by the lane change, on the adjacentlane. In the example illustrated in FIG. 3, the first target space SP2 cis increased while the second target space SP3 c is reduced. Thus, theECU 10 selects the first target space SP2 c. This is because it isconsidered that the host vehicle 1 can move more safely to the increasedfirst target space SP2 c than to the reduced second target space SP3 con the adjacent lane by the lane change.

Next, the ECU 10 uses the first target space SP2 c and the first targetpoint P2 c, which are selected as described above, to calculates thespeed of the host vehicle 1, at which the host vehicle 1 follows thefirst target point P2 c, on the basis of a relative speed and a relativedistance between the host vehicle 1 to the first target point P2 c.Based on the relative speed between the speed of this host vehicle 1 andthe speed of the peripheral vehicle 3 c, which serves as the precedingvehicle when the host vehicle 1 changes the lane to the first targetspace SP2 c, and the like, the ECU 10 determines a possibility of acollision of the host vehicle 1 with the peripheral vehicle 3 c at thetime when the host vehicle 1 changes the lane. In the exampleillustrated in FIG. 3, the ECU 10 determines that there is nopossibility of the collision.

Next, the ECU 10 further determines whether the relative distancebetween the host vehicle 1 and the first target point P2 c is shorterthan the specified distance (for example, 5 m) and the relative speedbetween the host vehicle 1 and the first target point P2 c is lower thanthe specified speed (for example, 5 to 10 km). In the exampleillustrated in FIG. 3, the ECU 10 determines that the relative distanceis shorter than the specified distance and that the relative speed islower than the specified speed. Then, the ECU 10 decides to adopt thefirst target point P2 c as the travel mediating point, and sets a routeL2 that connects the current position of the host vehicle 1 and thetravel mediating point P2 c (for example, the route L2 may be generatedby using the specified curve (the polynomial function or the like)) asthe target travel route for the lane change. The driving control isexecuted by using such a target travel route L2. In this case, when therelative speed between the speed of the host vehicle 1 and a movingspeed of the first target point P2 c (primarily, a moving speed of thefirst target space SP2 c) is lower than the specified speed after thelapse of the second time from the current time, the host vehicle 1starts changing the lane. Furthermore, the ECU 10 sets the speed, whichshould be applied to the host vehicle 1, on the above target travelroute L2. In the example illustrated in FIG. 3, the ECU 10 sets such aspeed that accelerates the host vehicle 1 (see an arrow A2) for the lanechange.

Next, a description will be made on a flow of processing that isexecuted by the ECU 10 in the embodiment of the present disclosure withreference to FIG. 4 to FIG. 7. FIG. 4 is a flowchart illustrating theoverall processing according to the embodiment of the presentdisclosure. FIG. 5 is a flowchart illustrating processing (firstprocessing) to generate the target travel route by the method asillustrated in FIG. 2 in the case where the point at which the hostvehicle 1 should change the lane is located relatively far away in theembodiment of the present disclosure. FIG. 6 is a flowchart illustratingprocessing (second processing) to generate the target travel route bythe method as illustrated in FIG. 3 in the case where the point at whichthe host vehicle 1 should change the lane is located relatively close tothe host vehicle 1 in the embodiment of the present disclosure. FIG. 7is a flowchart illustrating processing (target space followingprocessing) to follow the target space until the second time(hereinafter appropriately referred to as a “lane change time”) thatcorresponds to the time required for the lane change elapses in theembodiment of the present disclosure.

The processing related to the flowchart in FIG. 4 is repeatedly executedby the ECU 10 in specified cycles (for example, every 0.05 to 0.2second). When the processing related to this flowchart is initiated, instep S101, the ECU 10 acquires various types of the information from theplural types of the sensors illustrated in FIG. 1 (particularly, thecamera 21, the radar 22, the vehicle speed sensor 23, the navigationsystem 30, and the like). In this case, the ECU 10 at least acquires thetravel road information and the obstacle information described above.

Next, in step S102, based on the travel road information and the like,the ECU 10 determines whether the travel road is branched or mergedbefore the host vehicle 1 arrives at a destination. As a result, if theECU 10 determines that the travel road is branched or merged (step S102:Yes), the processing proceeds to step S103. On the other hand, if theECU 10 determines that the travel road is neither branched nor merged(step S102: No), the processing that is related to the flowchartillustrated in FIG. 4 is terminated.

Next, in step S103, the ECU 10 determines whether a lane change requestof the vehicle 1 is present. For example, based on the travel roadinformation and the like, the ECU 10 determines whether the host vehicle1 has to change the lane due to branching or merging of the travel road.As a result, if the ECU 10 determines that the lane change request ispresent (step S103: Yes), the processing proceeds to step S104. On theother hand, if the ECU 10 determines that the lane change request isabsent (step S103: No), the processing that is related to the flowchartillustrated in FIG. 4 is terminated.

Next, in step S104, the ECU 10 acquires, from the travel roadinformation, a distance from the current position of the host vehicle 1to the branched point or the merging point. Then, in step S105, the ECU10 determines whether the distance to the branched point or the mergingpoint is equal to or longer than a first specified distance. Here, theECU 10 determines whether the branched point or the merging point islocated relatively far away, that is, whether it is currently in asituation where the target travel route should be generated by themethod as illustrated in FIG. 2. From such an intent of thedetermination, the first specified distance that is used for thedetermination in step S105 is set. Preferably, the first specifieddistance is set according to a type of the travel road. In one example,the first specified distance is set to approximately 1 km on acontrolled-access highway and is set to approximately 500 m on a publicroad.

As a result of step S105, if the ECU 10 determines that the distance tothe branched point or the merging point is equal to or longer than thefirst specified distance (step S105: Yes), the processing proceeds tostep S106. Then, the ECU 10 executes the first processing for generatingthe target travel route by the method as illustrated in FIG. 2. Adetailed description on this processing will be made below. On the otherhand, if the ECU 10 determines that the distance to the branched pointor the merging point is shorter than the first specified distance (stepS105: No), the processing proceeds to step S107.

In step S107, the ECU 10 determines whether the distance to the branchedpoint or the merging point is equal to or longer than a second specifieddistance (<the first specified distance). Here, the ECU 10 determineswhether the distance to the branched point or the merging point isextremely short and thus it is currently in a situation where it isdifficult to change the lane. From such an intent of the determination,the second specified distance that is used for the determination in stepS107 is set. Preferably, the second specified distance is set accordingto the type of the travel road. In one example, the second specifieddistance is set to approximately 100 m on the controlled-access highwayand is set to approximately 50 m on the public road.

As a result of step S107, if the ECU 10 determines that the distance tothe branched point or the merging point is equal to or longer than thesecond specified distance (step S107: Yes), the processing proceeds tostep S108. Then, the ECU 10 executes the second processing forgenerating the target travel route by the method as illustrated in FIG.3. A detailed description on this processing will be made below. On theother hand, if the ECU 10 determines that the distance to the branchedpoint or the merging point is shorter than the second specified distance(step S107: No), the processing proceeds to step S109. In this case, theECU 10 decides to cause the host vehicle 1 not to change the lane in thedriving assistance based on the target travel route (step S109), and theprocessing that is related to the flowchart illustrated in FIG. 4 isterminated.

Next, after steps S106, S108 described above, that is, after the firstprocessing or the second processing is terminated, the processingproceeds to step S110, and the ECU 10 generates the target travel routefor the lane change on the basis of the travel mediating pointdetermined by the first processing or the second processing. Forexample, the ECU 10 generates the target travel route through which thehost vehicle 1 arrives at the travel mediating point by the lane changeby using a specified curve such as the polynomial function. Then, theprocessing proceeds to step S111. The ECU 10 sends the control signal toat least one of the engine control system 3 l, the brake control system32, and the steering control system 33 such that the vehicle 1 travelsalong the generated target travel route, and executes at least one ofengine control, braking control, and steering control as the drivingcontrol. In this case where the travel mediating point is not decided bythe first processing or the second processing (a detail thereon will bedescribed below), the ECU 10 decides to cause the host vehicle 1 not tochange the lane in the driving assistance based on the target travelroute, and terminates the processing that is related to the flowchartillustrated in FIG. 4.

Next, a description will be made on the first processing that isexecuted in step S106 of FIG. 4 with reference to FIG. 5. When the firstprocessing is initiated, in step S201, the ECU 10 acquires, from theobstacle information acquired in above step S101, information on the twoperipheral vehicles, which exist near the host vehicle 1, on theadjacent lane as the change destination of the host vehicle 1. Morespecifically, the ECU 10 acquires information on the peripheral vehicle(the preceding vehicle) that is located ahead of the host vehicle 1 andis located the closest to the host vehicle 1 and information on theperipheral vehicle (the following vehicle) that is located behind thehost vehicle 1 and is located the closest to the host vehicle 1.

Next, in step S202, the ECU 10 sets the dangerous area around each ofthese two peripheral vehicles on the basis of the information on the twoperipheral vehicles acquired in step S201. More specifically, based onthe relative speed and the relative distance (the inter-vehiculardistance) between the host vehicle 1 and the preceding vehicle, the ECU10 calculates the THW and/or the TTC between the host vehicle 1 and thepreceding vehicle, and sets the dangerous area around the precedingvehicle from this THW and/or the TTC. In addition, based on the relativespeed and the relative distance (the inter-vehicular distance) betweenthe host vehicle 1 and the following vehicle, the ECU 10 calculates theTHW and/or the TTC between the host vehicle 1 and the following vehicle,and sets the dangerous area around the following vehicle from this THWand/or TTC. Furthermore, the ECU 10 sets the portions which is stretchedbehind the preceding vehicle and the following vehicle in the dangerousareas to be longer than the portions in front of the preceding vehicleand the following vehicle therein.

Next, in step S203, the ECU 10 sets the target space between thedangerous area of the preceding vehicle and the dangerous area of thefollowing vehicle set in step S202, and also sets the target point atthe center of this target space. Then, in step S204, the ECU 10 executesthe target space following processing in FIG. 7 on the basis of thethus-set target space and the like.

Next, a description will be made on the second processing that isexecuted in step S108 of FIG. 4 with reference to FIG. 6. When thesecond processing is initiated, in step S301, the ECU 10 acquires, fromthe obstacle information acquired in above step S101, information on thethree peripheral vehicles, which exist near the host vehicle 1, on theadjacent lane as the change destination of the host vehicle 1. Morespecifically, the ECU 10 acquires information on the peripheral vehicle(hereinafter appropriately referred to as a “second preceding vehicle”)that is located ahead of the host vehicle 1 and is located the closestto the host vehicle 1, information on the peripheral vehicle(hereinafter appropriately referred to as a “first preceding vehicle”)that is located immediately ahead of this second preceding vehicle, andinformation on the peripheral vehicle (the following vehicle) that islocated behind the host vehicle 1 and is located the closest to the hostvehicle 1. These first preceding vehicle, second preceding vehicle, andfollowing vehicle correspond to the “first peripheral vehicle”, the“second peripheral vehicle”, and the “third peripheral vehicle” in thepresent disclosure, respectively.

Next, in step S302, the ECU 10 sets the dangerous area around each ofthese three peripheral vehicles on the basis of the information on thethree peripheral vehicles acquired in step S301. More specifically,based on the relative speed and the relative distance (theinter-vehicular distance) between the host vehicle 1 and the firstpreceding vehicle, the ECU 10 calculates the THW and/or the TTC betweenthe host vehicle 1 and the first preceding vehicle, and sets thedangerous area around the first preceding vehicle from this THW and/orthe TTC. By a similar method thereto, the ECU 10 also sets the dangerousarea of each of the second preceding vehicle and the following vehicle.Furthermore, the ECU 10 sets the portions which is stretched behind thefirst preceding vehicle, the second preceding vehicle, and the followingvehicle in the dangerous areas to be longer than the portions in frontof the first preceding vehicle, the second preceding vehicle, and thefollowing vehicle therein.

Next, in step S303, the ECU 10 sets the target spaces on the basis ofthe dangerous areas set in step S302. More specifically, the ECU 10 setsa target space (a first target space) between the dangerous area of thefirst preceding vehicle and the dangerous area of the second precedingvehicle, and also sets a target space (a second target space) betweenthe dangerous area of the second preceding vehicle and the dangerousarea of the following vehicle.

Next, in step S304, the ECU 10 calculates changes in the first andsecond target spaces set in step S303. More specifically, the ECU 10calculates a change rate (a change speed) of size of each of the firstand second target spaces after the lane change time. In this case, basedon the relative speed between the host vehicle 1 and the first precedingvehicle, and the like, the ECU 10 calculates a speed at a front end ofthe first target space after the lane change time. In addition, based onthe relative speed between the host vehicle 1 and the second precedingvehicle, and the like, the ECU 10 calculates a speed at a rear end ofthe first target speed after the lane change time. Then, the ECU 10acquires the change rate of the size of the first target space fromthese speeds at the front end and the rear end of the first targetspace. Similarly, based on the relative speed between the host vehicle 1and the second preceding vehicle, and the like, the ECU 10 calculates aspeed at a front end of the second target space after the lane changetime. In addition, based on the relative speed between the host vehicle1 and the following vehicle, and the like, the ECU 10 calculates a speedat a rear end of the second target space after the lane change time.Then, the ECU 10 acquires the change rate of the size of the secondtarget space from these speeds at the front end and the rear end of thesecond target space. In addition to such a change rate of the size ofeach of the first and second target spaces, the ECU 10 calculates thesize itself of each of the first and second target spaces after the lanechange time.

Next, in step S305, based on the changes in the first and second targetspaces calculated in step S304, the ECU 10 selects one of the first andsecond target spaces that is appropriate as a space, to which the hostvehicle 1 should move by the lane change, on the adjacent lane. In oneexample, in the case where one of the first and second target spaces isincreased while the other is reduced, the ECU 10 selects the targetspace that is increased. In another example, in the case where both ofthe first and second target spaces are increased, the ECU 10 selects thetarget space with a higher increase rate or the target space in largersize (that is, the target space, a length of which along the stretchingdirection of the travel road is longer). In further another example, inthe case where both of the first and second target spaces are notincreased, that is, in the case where both of the first and secondtarget spaces are reduced or are in constant size, the ECU 10 selectsthe target space with the lower change rate. In yet another example, inthe case where both of the first and second target spaces are reducedand only when the size of one or both of the first and second targetspaces is equal to or larger than a specified value, the ECU 10 selectsthe larger target space of the first and second target spaces. In thisexample, in the case where the size of both of the first and secondtarget spaces is smaller than the specified value, the ECU 10 neitherselects the first nor second target space. In further another example,in the case the changes in the size of the first and second targetspaces are substantially the same, and/or in the case where the size ofthe first and second target spaces is the same, the ECU 10 selects thesecond target space that is located behind. This is because it isconsidered to be safer when the host vehicle 1 is decelerated during thelane change and moves to the second target space at the rear than whenthe host vehicle 1 is accelerated during the lane change and moves tothe first target space in front. The plural examples described above mayappropriately be combined and implemented.

Then, in step S306, the ECU 10 executes the target space followingprocessing in FIG. 7 on the basis of the target space, which is selectedin step S305, and the like.

Next, a description will be made on the target space followingprocessing that is executed in step S204 of FIG. 5 and step S306 of FIG.6 with reference to FIG. 7. When the target space following processingis initiated, in step S401, the ECU 10 sets the dangerous area for eachof the two peripheral vehicles, each of which defines the target space(in the case of the second processing, the target space selected in suchprocessing) applied in the first or second processing described above.More specifically, the ECU 10 predicts the positions and the speeds ofthe peripheral vehicles and calculates the relative speed and therelative distance (the inter-vehicular distance) between the hostvehicle 1 and each of the peripheral vehicles by using the Kalman filteror the like. Then, the ECU 10 sets the dangerous area around each of theperipheral vehicles on the basis of the THW and/or the TTC according tothe relative speed and the relative distance between the host vehicle 1and each of the peripheral vehicles.

Next, in step S402, the ECU 10 sets the target space between thedangerous areas that are set around the two peripheral vehicles in stepS401. In addition, the ECU 10 sets the target point at the center ofthis target space.

Next, in step S403, the ECU 10 calculates acceleration/deceleration forthe host vehicle 1 to follow the target point that is set in step S402.More specifically, based on the relative speed and the relative distancebetween the host vehicle 1 and the target point, the ECU 10 calculatesthe acceleration/deceleration for the host vehicle 1 to follow thetarget point. Then, in step S404, the ECU 10 calculates the speed of thehost vehicle 1, to which the calculated acceleration/deceleration isapplied, that is, the speed of the host vehicle 1 for following thetarget point.

Next, in step S405, based on the speed of the host vehicle 1 that iscalculated in step S404, the ECU 10 determines whether there is apossibility that the host vehicle 1 collides with the preceding vehicledefining the target space when the host vehicle 1 changes the lane. TheECU 10 calculates the TTC from the relative speed and the relativedistance between the host vehicle 1 and the preceding vehicle. Then, ifthis TTC is shorter than a specified time, the ECU 10 determines thatthere is the possibility that the host vehicle 1 collides with thepreceding vehicle (step S405: No). In this case, the ECU 10 terminatesthe processing that is related to the flowchart illustrated in FIG. 7without setting the travel mediating point that defines the targettravel route for the lane change, in other words, without setting thetarget point as the travel mediating point. On the other hand, if theTTC is equal to or longer than the specified time, the ECU 10 determinesthat there is no possibility of the collision between the host vehicle 1and the preceding vehicle (step S405: Yes), and the processing proceedsto step S406.

In step S406, the ECU 10 determines whether the lane change time haselapsed from the initiation of the target space following processing. Ifthe ECU 10 determines that the lane change time has elapsed (Step 406:Yes), the processing proceeds to step S407. On the other hand, if theECU 10 determines that the lane change time has not elapsed (Step 406:No), the processing returns to step S401. In this case, the ECU 10repeats the processing in steps S401 to S406 until the lane change timeelapses.

Next, in step S407, the ECU 10 calculates a relative distance and arelative speed between the host vehicle 1 and the target point. Then, instep S408, the ECU 10 determines whether the relative distance betweenthe host vehicle 1 and the target point is shorter than the specifieddistance (for example, 5 m) and the relative speed between the hostvehicle 1 and the target point is lower than the specified speed (forexample, 5 to 10 km). Here, the ECU 10 determines whether a relativerelationship between the host vehicle 1 and the target space is in astate where the host vehicle 1 can safely and reliably move to thetarget space.

As a result of step S408, if the relative distance of the host vehicle 1to the target point is shorter than the specified distance and therelative speed of the host vehicle 1 to the target point is lower thanthe specified speed (step S408: Yes), the processing proceeds to stepS409. Then, the ECU 10 sets this target point as the travel mediatingpoint that defines the target travel route for the lane change. On theother hand, if the relative distance of the host vehicle 1 to the targetpoint is equal to or longer than the specified distance, or if therelative speed of the host vehicle 1 to the target point is equal to orhigher than the specified speed (step S408: No), the ECU 10 terminatesthe processing that is related to the flowchart illustrated in FIG. 7without setting the target point as the travel mediating point.

Operation and Effects

Next, a description will be made on an operation and effects accordingto the embodiment of the present disclosure.

According to this embodiment, in the case where the host vehicle 1changes the lane, the ECU 10 sets the target space, to which the hostvehicle 1 should move, between the peripheral vehicles on the changedestination lane, predicts the future position of this target space onthe basis of the moving speed of the target space, and generates thetarget travel route, on which the host vehicle 1 travels during the lanechange, on the basis of the predicted future position. In this way, itis possible to accurately recognize the position of the space betweenthe peripheral vehicles that is changed according to the peripheralvehicles, each of which moves at various speeds from time to time. As aresult, when the host vehicle 1 changes the lane by the drivingassistance based on the target travel route, the host vehicle 1 cansafely move to the position between the peripheral vehicles on thechange destination lane.

According to this embodiment, the ECU 10 sets the dangerous area aroundeach of the two peripheral vehicles, and sets the target space, to whichthe host vehicle 1 should move, between these dangerous areas on thechange destination lane. In this way, when the host vehicle 1 changesthe lane and moves to the target space by the driving assistance basedon the target travel route, it is possible to effectively prevent thecollision of the host vehicle 1 with the peripheral vehicle.

According to this embodiment, the ECU 10 sets the portion, which isstretched behind the peripheral vehicle, in the dangerous area to belonger than the portion, which is stretched ahead of the peripheralvehicle, in the dangerous area. Thus, it is possible to effectivelyprevent the collision of the host vehicle 1 with the peripheral vehiclein the case where the peripheral vehicle is decelerated during the lanechange of the host vehicle 1.

According to this embodiment, the ECU 10 generates such a target travelroute that the host vehicle 1 starts changing the lane when the relativespeed between the speed of the host vehicle 1 and the moving speed ofthe target space (primarily, the moving speed of the target point)becomes lower than the specified speed. In this way, when the hostvehicle 1 changes the lane by the driving assistance based on the targettravel route, the host vehicle 1 can safely and reliably move to thetarget space.

Meanwhile, according to this embodiment, in the case where the hostvehicle 1 changes the lane, the ECU 10 sets the target space, to whichthe host vehicle 1 should move, between the peripheral vehicles on thechange destination lane, predicts the change in the size of this targetspace, and generates the target travel route, on which the host vehicle1 travels during the lane change, on the basis of the change in the sizeof the predicted target space. In this way, it is possible to accuratelyrecognize the size of the space between the peripheral vehicles that ischanged according to the peripheral vehicles, each of which moves at thevarious speeds from time to time. As a result, when the host vehicle 1changes the lane by the driving assistance based on the target travelroute, the host vehicle 1 can safely move to the position between theperipheral vehicles on the change destination lane.

According to this embodiment, the ECU 10 sets the two target spaces (thefirst and second target spaces) on the change destination lane, selectsone of the target spaces on the basis of the change in the size of eachof these two target spaces, and generates the target travel route on thebasis of the selected target space. In this way, of the spaces betweenthe two peripheral vehicles existing near the host vehicle 1 on thechange destination lane, the space that is adequate for the movement ofthe host vehicle 1 is accurately adopted, and the target travel routecan thereby be generated.

According to this embodiment, in the case where one of the first andsecond target spaces is increased while the other is not increased, theECU 10 selects the target space that is increased. In this way, it ispossible to accurately adopt the target space, to which the host vehicle1 moves for the lane change, on the adjacent lane. This is because it isconsidered that the host vehicle 1 can move more safely to the increasedtarget space than to the reduced target space.

According to this embodiment, in the case where both of the first andsecond target spaces are not increased, that is, in the case where bothof the first and second target spaces are reduced or are in the constantsize, the ECU 10 selects the target space with the lower change rate.Also, in this way, it is possible to accurately adopt the target space,to which the host vehicle 1 can further safely move, on the adjacentlane in the lane change. This is because, in this case, it is consideredto be safe that the host vehicle 1 moves to the target space with thelower change rate in this case.

According to this embodiment, in the case where both of the first andsecond target spaces are reduced and the size of one or both of thefirst and second target spaces is equal to or larger than the specifiedvalue, the ECU 10 selects the larger target space of the first andsecond target spaces. Also, in this way, it is possible to accuratelyadopt the target space, to which the host vehicle 1 can further safelymove, on the adjacent lane in the lane change. This is because, in thiscase, it is considered that the host vehicle 1 moves safely to thistarget space when the target space is reduced but is still large enough.

According to this embodiment, in the case where the change in the sizeof the first and second target spaces is substantially the same, the ECU10 selects the second target space. Also, in this way, it is possible toaccurately adopt the target space, to which the host vehicle 1 canfurther safely move, on the adjacent lane in the lane change. This isbecause, in this case, it is considered to be safer when the hostvehicle 1 is decelerated during the lane change and moves to the secondtarget space at the rear than when the host vehicle 1 is acceleratedduring the lane change and moves to the first target space in front.

According to this embodiment, in the case where the distance to thepoint, at which the host vehicle 1 should change the lane, is equal toor longer than the specified distance, the ECU 10 predicts the futureposition of the target space on the basis of the moving speed of thetarget space and generates the target travel route, on which the hostvehicle 1 travels during the lane change, on the basis of the predictedfuture position. On the other hand, in the case where the distance tothe point, at which the host vehicle 1 should change the lane, isshorter than the specified distance, the ECU 10 predicts the change inthe size of the target space and generates the target travel route, onwhich the host vehicle 1 travels during the lane change, on the basis ofthe change in the size of the predicted target space. In this way, it ispossible to appropriately switch the processing to generate the targettravel route on the basis of the target space according to whether thepoint, at which the host vehicle 1 should change the lane, is locatedfar away from or near the host vehicle 1.

MODIFIED EXAMPLES

In the embodiment described above, in the first processing, the targettravel route is generated on the basis of the single target space thatis defined by the two peripheral vehicles (see FIG. 2). In anotherexample, the target travel route may be generated on the basis of thetwo or more target spaces that are defined by the three or moreperipheral vehicles. In addition, in the embodiment described above, inthe second processing, the target travel route is generated on the basisof the two target spaces that are defined by the three peripheralvehicles (see FIG. 3). In another example, the target travel route maybe generated on the basis of the three or more target spaces that aredefined by the four or more peripheral vehicles.

In the embodiment described above, the example in which the presentdisclosure is applied to the vehicle 1 having the engine as a drivesource has been described (see FIG. 1). However, the present disclosurecan also be applied to a vehicle having an electric motor as the drivesource (an electric vehicle or a hybrid vehicle). In addition, in theabove-described embodiment, the braking force is applied to the vehicle1 by the brake system (the brake control system 32). However, in anotherexample, the braking force may be applied to the vehicle by regenerationof the electric motor.

DESCRIPTION OF REFERENCE SIGNS AND NUMERALS

-   -   1 Vehicle (host vehicle)    -   3 a to 3 e Peripheral vehicle    -   10 ECU    -   21 Camera    -   22 Radar    -   30 Navigation system    -   31 Engine control system    -   32 Brake control system    -   33 Steering control system    -   100 Vehicle driving assistance system

1. A travel route generation system comprising: a travel roadinformation acquisition sensor that acquires travel road information ona travel road of a host vehicle; an obstacle information acquisitionsensor that acquires obstacle information on an obstacle on the travelroad; and circuitry configured to generate a target travel route, onwhich the host vehicle travels, along the travel road based on thetravel road information and the obstacle information, wherein thecircuitry is further configured to: acquire information on at least twoperipheral vehicles, which exist near the host vehicle, on a changedestination lane, from the obstacle information under a condition it isplanned for the host vehicle to change lanes; set a target space, towhich the host vehicle should move, between the at least two peripheralvehicles in the change destination lane based on the information on theat least two peripheral vehicles; predict a change in size of the targetspace; and generate the target travel route, on which the host vehicletravels during a lane change operation, based on the predicted change inthe size of the target space.
 2. The travel route generation systemaccording to claim 1, wherein the circuitry is further configured to:acquire information on a first peripheral vehicle of the at least twoperipheral vehicles that exists on the change destination lane,information on a second peripheral vehicle of the at least twoperipheral vehicles and that exists behind the first peripheral vehicle,and information on a third peripheral vehicle of the at least twoperipheral vehicles that exists behind the second peripheral vehicle asthe information on the at least two peripheral vehicles; set a firsttarget space between the first peripheral vehicle and the secondperipheral vehicle and a second target space between the secondperipheral vehicle and the third peripheral vehicle as the target spacesbased on the information on the first, second, and third peripheralvehicles; select one of the first target space and second target spacebased on the change in the size of each of the first target space andthe second target space; and generate the target travel route based onthe selected target space.
 3. The travel route generation systemaccording to claim 2, wherein the circuitry is further configured toselect a target space that is increased under a condition in which oneof the first target space and the second target space is increased whilethe other is not increased.
 4. The travel route generation systemaccording to claim 3, wherein the circuitry is further configured toselect a target space with a lower change rate of size under a conditionwhere both of the first target space and the second target space are notincreased.
 5. The travel route generation system according to claim 3,wherein the circuitry is further configured to select a larger targetspace of the first target space and the second target space under acondition where both of the first target space and the second targetspace are reduced and the size of one or both of the first target spaceand the second target space is equal to or larger than a specifiedvalue.
 6. The travel route generation system according to claim 5,wherein the circuitry is further configured to select the second targetspace under a condition where the change in size of the first targetspace and the second target spaces is substantially the same.
 7. Thetravel route generation system according to claim 6, wherein thecircuitry is further configured to: set a first dangerous area that thehost vehicle does not enter around the first peripheral vehicle and asecond dangerous area around the second peripheral vehicle based on theinformation on said at least two peripheral vehicles; set the targetspace between the first dangerous area and the second dangerous area;and set a first portion that is stretched in the first dangerous areabehind the first peripheral vehicle in the first dangerous area to belonger than a second portion stretched ahead of the first peripheralvehicle in the first dangerous area.
 8. The travel route generationsystem according to claim 7, wherein the circuitry is further configuredto generate such a target travel route in response to the lane changeoperation that occurs for the host vehicle in response to a relativespeed between a speed of the host vehicle and a moving speed of thetarget space being lower than a specified speed.
 9. The travel routegeneration system according to claim 8, wherein the circuitry is furtherconfigured to: generate the target travel route, on which the hostvehicle travels during the lane change operation, based on the predictedchange in the size of the target space under a condition where adistance to a point, at which the host vehicle is planned to changelanes, is shorter than a specified distance; and predict a futureposition of the target space on the basis of the moving speed of saidtarget space and generate the target travel route, on which the hostvehicle travels during the lane change operation, based on the predictedfuture position under a condition where the distance to the point, atwhich the host vehicle is planned to change lanes, is equal to or longerthan the specified distance.
 10. The travel route generation systemaccording to claim 1, further comprising: a controller configured toexecute driving control of the host vehicle such that the host vehicletravels along the target travel route.
 11. The travel route generationsystem according to claim 1, wherein the circuitry is further configuredto: set a first dangerous area that the host vehicle does not enteraround a first peripheral vehicle of the at least two peripheralvehicles and a second dangerous area around a second peripheral vehicleof the at least two peripheral vehicles based on the information on saidat least two peripheral vehicles; set the target space between the firstdangerous area and the second dangerous area; and set a first portionthat is stretched in the first dangerous area behind the firstperipheral vehicle in the first dangerous area to be longer than asecond portion stretched ahead of the first peripheral vehicle in thefirst dangerous area.
 12. The travel route generation system accordingto claim 1, wherein the circuitry is further configured to generate sucha target travel route in response to the lane change operation thatoccurs for the host vehicle in response to a relative speed between aspeed of the host vehicle and a moving speed of the target space beinglower than a specified speed.
 13. The travel route generation systemaccording to claim 1, wherein the circuitry is further configured to:generate the target travel route, on which the host vehicle travelsduring the lane change operation, based on the predicted change in thesize of the target space under a condition where a distance to a point,at which the host vehicle is planned to change lanes, is shorter than aspecified distance; and predict a future position of the target space onthe basis of the moving speed of said target space and generate thetarget travel route, on which the host vehicle travels during the lanechange operation, based on the predicted future position under acondition where the distance to the point, at which the host vehicle isplanned to change lanes, is equal to or longer than the specifieddistance.
 14. The travel route generation system according to claim 1,further comprising: a controller configured to execute driving controlof the host vehicle such that the host vehicle travels along the targettravel route.
 15. The travel route generation system according to claim2, wherein the circuitry is further configured to select a target spacewith a lower change rate of size under a condition where both of thefirst target space and the second target space are not increased. 16.The travel route generation system according to claim 2, wherein thecircuitry is further configured to select a larger target space of thefirst target space and the second target space under a condition whereboth of the first target space and the second target space are reducedand the size of one or both of the first target space and the secondtarget space is equal to or larger than a specified value.
 17. Thetravel route generation system according to claim 2, wherein thecircuitry is further configured to select the second target space undera condition where the change in size of the first target space and thesecond target spaces is substantially the same.
 18. The travel routegeneration system according to claim 15, wherein the circuitry isfurther configured to select a larger target space of the first targetspace and the second target space under a condition where both of thefirst target space and the second target space are reduced and the sizeof one or both of the first target space and the second target space isequal to or larger than a specified value.
 19. The travel routegeneration system according to claim 15, wherein the circuitry isfurther configured to select the second target space under a conditionwhere the change in size of the first target space and the second targetspaces is substantially the same.
 20. The travel route generation systemaccording to claim 16, wherein the circuitry is further configured toselect the second target space under a condition where the change insize of the first target space and the second target spaces issubstantially the same.